Mesoscale Variability On The Eastern Brazilian Shelf Through A ROMS Nested Model

L. F. Rezende (1,2), P. Silva (1), A. Peliz (1), J. Dubert (1) and M. Cirano (3)

(1) Departamento de Física, Universidade de Aveiro, Portugal
(2) Universidade Estadual de Santa Cruz, Brazil
(3) Universidade Federal da Bahia, Brazil


The Eastern Brazilian Shelf is a narrow, oligotrophic and bathymetrically complex shelf, on the southwestern South Atlantic. On such narrow shelves, ocean – shelf interactions processes are regarded as effective mechanisms promoting nutrient enrichment and shelf circulation variability.

In this work, we present results of ongoing modeling research concerning the mesoscale variability off the Brazilian coast between 7° – 20° S. The numerical model used is a primitive, nested, three dimensional, stretched terrains - following coordinate, Regional Ocean Modeling System – ROMS. The larger scale grid has a resolution of 1/4° in longitude and latitude and describes the general features of the large ocean circulation in the South Atlantic. This grid was nested on a mesoscale grid of 1/12° encompassing the area of study. The model was initiated for both climatological and global models outputs (e.g. LEVITUS and SODA).

Model validation is based on the analysis of the mesoscale variability on eddy kinetic energy (EKE), calculated from five years TOPEX/ Poseidon and ERS Combined data for sea level anomaly (SLA). Recurrent eddy activities are frequently noticed on the mesoscale grid. Preliminary estimates of the cross-shelf transport are discussed.